The Ground Moving Target Indicator is a specific type of radar typically employed as a tactical sensor and used by our armed forces to detect movement generated by discrete, non-stationary, ground-based targets at given locations and instances in time. These movements are detected by the well-known Doppler Effect where radar echoes are exploited in a manner that allows the Ground Moving Target Indicator (“GMTI”) to distinguish frequency shift(s) relative to its own carrier frequency. Because this shift is proportional to the target's range rate, the GMTI can accurately locate where the target is with respect to its own location.
GMTI sensors operate in the Radio Frequency (RF) spectrum where human visual perception is limited and therefore, RF electronics are required to interpret the target information. With the advent of more reliable RF electronic devices for transceiving these transient signals, it is now possible to convert the transient signals into digitized data. This is extremely useful for testing since the user is able to validate the effectiveness and accuracy of the GMTI sensor.
Despite digitizing the test data, current GMTI sensor test techniques still suffer from a number of problems with performance characterization and the inability to adequately preserve the quality of data following distribution. The current test method for assessing GMTI sensor accuracy and performance is to analyze and interpret range-Doppler maps showing raw radar returns on an image. These range-Doppler maps are then progressively stepped in sequence according to time and the movement of the Doppler generators. FIG. 1 is an example of a prior art range-Doppler map of raw radar returns that shows intrinsic endoclutter as a central cluster 1 spread vertically along the range dimension and about the main radar beam with the Doppler generators of interest being indicated by a number of exoclutter points 2. While the Doppler generators of interest have a finite Signal-to-Noise ratio with a defined threshold detector allowing them to be distinguished from the presence of noise, the FIG. 1 prior art range-Doppler map only provides a rather blurred, fuzzy and imprecise characterization of GMTI sensor performance.
In addition to the FIG. 1 prior art Doppler exoclutter points of interest being blurred, fuzzy and imprecise, the procedure for displaying raw radar returns does not provide any statistical information or ground comparisons. Another limitation of the prior art range-Doppler map is that they are often collected in a proprietary format making them inaccessible by other users in the radar community. Thus, there has been a long-felt need for a GMTI test technique that displays radar returns in a less cumbersome and more efficient manner while preserving a standardized format readily accessible by other users.
In order to overcome the prior art's shortcomings and limitations caused by the inability to preserve data quality in the range-Doppler map, there has been a long-felt need to gather test data in a more familiar and standardized format. The standardized information sources used for artillery testing data collection system is the NATO-EX standard, and none of the currently available GMTI testing techniques use the NATO-EX system. Up until now, there is no available GMTI sensor test technique that provides the necessary clear characterization, less cumbersome operation and adequate preservation of test data needed to overcome the long-felt disadvantages, shortcomings and limitations of the prior art GMTI test systems using the range-Doppler map.